Processes which convert molten aluminum to alumina/aluminum composite through vapor-phase oxidation have been developed by several individuals and companies, including for example, the Lanxide Corporation. The Lanxide DIMOX (directed metal oxidation) processes for preparing ceramic-metal composites requires vapor-phase transport for producing composite product. The Lanxide process (Newkirk, et al., J. Mater. Res. 1(1), January/February 1986, page 81-89) involves oxidation of a bulk molten metal, usually in an inert graphite or alumina crucible, by a gas to produce a solid ceramic-containing body via a directed growth process. The reaction product forms initially on the exposed surface of a pool of the molten metal and then grows outward, fed by transport of additional metal through channels in the ceramic product of the oxidation reaction between the parent metal and the gas phase oxidant. Direct oxidation reaction between silica-containing preform and molten aluminum alloy is not taught.
Brondyke has observed the chemical interaction between molten aluminum and silica. (Brondyke, J. Am. Cerm. Soc., 36 [5] 171-74 (1953)).
Standage et al., in J. Am. Cerm. Soc., vol. 50, no. 2, page 101-105, 1967, teach the reaction between vitreous silica and molten aluminum.
Prabriputaloong et al., J. Am. Ceram. Soc., April 1973, page 184-85, discusses the reduction of SiO.sub.2 by molten aluminum.
It is known that infiltration of ceramic materials (e.g. Al.sub.2 O.sub.3) with molten metal can result in metal/ceramic composites.
Prior art processes for the fabrication of alumina/aluminum matrix composites suffer from the limitation in three dimensional growth which tends to restrict the shape of the resulting composite articles. In addition, prior art processes require gas phase reaction. Finally, metal-ceramic articles produced by the conventional methods exhibit undesirable porosity, anisotropy and poor toughness for many applications.
There exists a need for a non-vapor phase process for the production of metal-ceramic articles with increased densification, improved ability to tailor the microhardness and toughness, and which process will produce articles of a predetermined arbitrary shape.